This invention relates generally to apparatus and methods for monitoring the operation of cyclones of the type adapted to carry out centrifugal separating operations.
Cyclones such as are employed for effecting centrifugal separation operations on a variety of feed materials, such as pulps and slurries, are customarily made with a cylindrical body section having a tangentially disposed feed inlet and a lower conical shaped body section terminating in an apex having an underflow orifice. The overflow is discharged through a centrally located pipe or vortex finder. In normal operations swirling movement is imparted to the body of material within the cyclone, whereby separating forces cause heavier components of the feed to be separated and discharged through the underflow orifice, with an overflow being continuously discharged through the vortex finder. Normally the underflow is discharged as a spray having a hollow conical shaped pattern or configuration. Various abnormal operating conditions serve to prevent the discharge of the underflow in the normal pattern. For example, oversized rocks or lumps in the feed material may choke or partially choke the underflow discharge orifice, thus interferring with the development of the usual conical spray pattern. Also under certain conditions, such as improper loading, material is discharged from the underflow orifices as a solid stream or rope. In the various industries where such separating cyclones are employed it is important to detect malfunctioning of a cyclone, and to disconnect it from the system, without interferring with the operation of other cyclones which may be incorporated in the system. In some instances one or more cyclones are connected to a closed circuit milling system, such as a ball or other grinding mill circuit operating on ore solids to produce a pulp or slurry of suitable concentration. In such a system abnormal operation that is visually noted may enable the operator to correct operation of the milling system and thus restore proper loading of the cyclones.
U.S. Pat. No. 3,114,510 granted Dec. 17, 1963, discloses means making use of conductive probes in the form of insulated rods extending into the underflow spray pattern of a cyclone, and connected to circuitry which provides a signal response in the event there is a substantial change in the spray pattern. The input to the circuitry in that instance employs three insulated conductors, one being connected to the metal body of the cyclone and the other two to the probes. The tip end of the probes, which are uninsulated, are disposed adjacent the inner and outer peripheries of the hollow conical shaped spray. A substantial change in the resistivity between one probe and the metal body of the cyclone indicates a change in the spray pattern such that the spray is no longer enveloping the tip end of that probe. Likewise, a change in the resistance between the tip end of the other probe and the body of the cyclone indicates a change in that boundary of the pattern with which that particular probe is associated. As disclosed in said patent, the associated circuitry serves to generate a response signal which may be used to control the feed to a grinding mill which is employed to reduce the particle size of the feed solids, and thus adjust the loading of the cyclone. Also the patent shows use of a generated signal for adjusting valve means for controlling the rate of discharge of underflow material.